Activated carbon has long been used to remove toxic gases and vapors from a stream of gas or liquid. For example, activated carbons are also useful for removing noxious agents from breathing air or exhaust gases and can be used in gas mask filters, respirators, collective filters, and other applications. Activated carbons used to remove noxious agents are often impregnated with components that react with noxious gases that would otherwise not be removed through the use of unimpregnated activated carbons. Chemical adsorption reactions with impregnants on the activated carbon render noxious gasses as inert or convert them to a form that is more readily removed by the carbon. In particular, nitrogen dioxide and related nitrogen oxides (NOx) are poisonous gases that must be removed from breathing air or exhaust gases. Previous adsorbents have used various carbon-based and non-carbon-based sorbents with high costs and low effectiveness.
Further, the use of triethylenediamine (TEDA) in respiratory filters and sorbent media designed to provide respiratory protection against military gases has long been recognized. In particular, TEDA is accepted as a critical material in providing protection against cyanogen chloride (CK) gas in chromium-free compositions, which may also contain copper and in some cases zinc. There is a desire to improve NO2 removal for many respirator and air purification applications.